Circuit controlling apparatus



Sept 8, 1942. E A, L A H 2,295,348

CIRCUIT CONTROLLING APPARATUS Filed July 23, 1940 Inventor: Edward A. Leach,

b Jv m a. QWJ y His Attorney Patented s pt- 8, 1942 Edward a. Leach, Schenectady, N. Y., assignmto General Electric Company, a corporation of New York Application July 23, 1940, Serial No. 346,971

llOlaims.

This invention relates to circuit controlling apparatus and more particularly to adjustable inductances carrying high frequency currents.

Adjustable inductances are often formed by wire supported on a rotatable frangible cylinder,

such as a ceramic coil form supported on a shaft, and cooperating with a contact which follows the turns of wire as the coil is rotated. It is an object of my invention to provide means for mounting such frangible bodies upon a shaft, which means is arranged to reduce to a minimum the breakage of the frangible bodies during their mounting.

The contact which cooperates with such a rotating coil may be a wheel, so placed that the turns of the coil travel thereunder to maintain contact continuously between the wire and the wheel. At either end of the wire coil, fastenings are provided to attach the wire to the ceramic form. When the contact hits such a fastening while the coil is turning, the ceramic form comes to an abrupt stop, which may break the form. It is, therefore, a further object of my invention to provide for mounting a frangible body to rotate with a shaft subject to sudden stops, which mounting means minimizes the danger of breakage of the frangible body upon its abrupt stopping.

It is a still further object of my invention to provide such a rotatable inductance coil havinz an improved contact. wheel cooperating there-- with.

The features of my invention which I believe to be novel are set forth with particularity in the appended claims. My invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof may best be understood by reference to the following description taken in connection with the accompanying drawing in which Fig. l is a side view, partly in section, of an inductance constructed according to my invention; Fig. 2 is a sectional end view of the same inductance; Fig. 3 is a view, partly in section, of

certain parts of the apparatus of Fig. 1; and- Ilg. 4 is a sectional side view of the parts illustrated by Fig. 3.

In Fig. 1 a shaft i carries a ceramic coil form II for rotation therewith and a coil I2 of conducting wire wound upon the ceramic form ll. Parallel to the shaft I0 is a conducting shaft it upon which a contact wheel I4 is mounted to turn upon the wire forming the coil l2 and to maintain a conductive connection between the coil l2 andthe shaft l3.

Resilient means, not

shown, are provided at each end of the shaft II to maintain it and the wheel ll pressed against the coil l2.

The ceramic form I l extends between a pair of insulating end plates i5 and it, within which the shaft II is journaled. The plates i5 and it are maintained in fixed relation to each other by rods ii. A handwheel i8 is connected through a'ilexible coupling ID to the shaft It to provide for manual rotation of the ceramic form ll.

At each end the coil of wire [2 is fastened to the ceramic form H by a connection 20, of which only one is shown. An operator can spin the ceramic form with the coil l2 thereon at high speed by the handwheel I8. When the contact wheel it reaches either end of its travel along the coil l2, one of the connections 20 comes into sudden contact with the wheel ll so that the ceramic form H is stopped very suddenly.

The ceramic form ii is supported from the shaft ill in such a way that sudden stops of this nature are least likely to cause breakage of the ceramic form. The nature of this support may be easily seen in Fig. 2, which shows that the form II is supplied with a pair of holes 2i and 22 opposite each other. It is also supplied with a second pair of holes 23 and 24 equally spaced between the first mentioned holes and also opposite each other. Two pieces of stiff spring wire 25 and 26 are passed through the holes 2| and 22, one, around each side of the shaft ll. Two other pieces of stifl spring wire 21 and 2| are passed through the holes 23 and 24 and also on opposite sides of the shaft Hi.

The wires 25, 26, 21 and 28 are secured where they touch the shaft l0 and adjacent ends of the wires within the holes 2i, 22, 23 and 24 are soldered together. Such a supporting structure has two great advantages, namely, during assembly of the ceramic form, the shaft in and the support wires, no stress is produced in the ceramic form, and during sudden'stops of the ceramic form II,- it is free to move rotationally around 'the shaft ill to a slight extent due to the resilience of the wires 25, 26, 21 and 28, so that breakage of the form Ii due to shocks is minimized.

Fig. 1 shows such a resilient support provided between the ceramic form H and the shaft It at the right end of the form. This support com-- prises a resilient wire 3i passing from the hole 29 around one side of the shaft l0 and to the hole 30. A similar hole such as that indicated at 23 is provided at the left end of the form to receive similar spring members.

within very wide limits. It has been found that this resistance change occurs almost entirely between the contact wheel H and the shaft l3. The resistance change was found to be especially large in wheel structures requiring lubrication.

In accordance with my invention a constructionfor the contact wheel i4 is provided which minimizes any resistance change between it and the shaft l3.

Fig. 3 is an end view of the contact wheel ll, partly in section, showing its manner of support on the shaft l3. A bushing 32 is provided within the wheel H to act as a raceway for ball bearings 33 between the bushing 32 and the shaft I3. 'Iwo pieces of spring metal 34 and 35 are placed in the space between the bushing 32 and the shaft i3 so 7 as to lie in a distorted shape and bear with substantial force against the bushing 32 while sliding around the shaft i3 when the wheel it turns.

In Fig. 4 it may be seen that a second bushing 36 and a second set of ball bearings 31 is provided on that side of the wheel opposite to the bushing 32. The provision of the ball bearings makes unnecessary the use of lubricant, which was found to be highly undesirable.

In order to maintain the resistance between the shaft i3 and the coil l2 most nearly uniform, and

at the same time to maintain satisfactory wearing qualities, it is preferred to make the wheel i4 and the shaft l3 of a beryllium-copper alloy. Heat treated beryllium-copper alloy is sumciently hard so that the ball bearings 33 when unlubricated cannot cut grooves in the shaft l3. Also the wheel l4, when it is struck by one of the connections 20, is not dented.

The ball bearings 33 are provided in order to maintain accurate alignment between the wheel H and the conducting shaft i3, so that the pieces 34 and 35 of spring metal may accurately maintain a wiping metal-to-metal contact between the wheel 14 and the conducting shaft l3. It has been found thatan adjustable inductance constructed in this manner and having parts of these particular materials has very desirable wear resistance qualities, maintains a low resistance therethrough, and has a sufficiently small change in resistance upon adjustment so that the inductance described in this application may be used in oscillators whose stability in frequency must be high.

While I have shown a particular embodiment of my invention, it will of course be understood that I do not wish to be limited thereto since different modifications may be made, and I aim by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. Electric circuit controlling apparatus comprising a rotatable shaft, a frangible cylindrical coil form surrounding said shaft concentrically and having holes therethrough on opposite sides of said shaft, and a pair of resilient wires affixed to said shaft and extending substantially radially therefrom with their free ends fixedly engaged in.

said holes whereby said coil form is supported on said shaft and torsional resilience is provided therebetween to minimize breakage of said form.

2. Electric circuit controlling apparatus comprising a rotatable shaft, a frangible cylindrical coil form concentric with said shaft, means for supporting said form on said shaft and to provide torsional resilience therebetween, an inductance coil supported on said form, a conducting shaft parallel to said first shaft and adjacent said coil, and a contact wheel on said conducting shaft conductively engaged with said inductance coil to vary the circuit therethrou h, and conducting means between said wheel and said conducting shaft arranged to maintain a wiping metal-tometal path therebetween.

3. Electric circuit controlling apparatus comprising a rotatable shaft, a cylindrical body mounted on said shaft, an inductance coil supported on said body, a substantially stationary conducting shaft parallel to said first shaft and adjacent said coil, a contact wheel rotatable on said conducting shaft and conductively engaged with said coil to vary the circuit connection therethrough as said coil and wheel are rotated, and resilient conducting means so distorted between said wheel and said conducting shaft as to press apart said wheel and shaft and being slidably arranged between said wheel and shaft to maintain a wiping metal-to-metal path between said wheel and shaft.

4. Electric circuit controlling apparatus comprising a rotatable shaft, a cylindrical body mounted on said shaft, an inductance coil supported on said cylindrical body, a conducting shaft parallel t said first shaft and adjacent said coil, 9. contact wheel rotatable on said conducting shaft and conductively engaged with said coil to vary the circuit connection therethrough, resilient conducting means between said wheel and said conducting shaft so distorted therebetween as to press apart said wheel and conducting shaft to maintain a wiping metal-tometal path therebetween, and bearing means to maintain said wheel accurately aligned with said shaft, whereby said wiping metal-to-metal path is unaffected by misalignment of said wheel with said conducting shaft.

5. Electric circuit controlling apparatus comprising a rotatable shaft, a frangible cylindrical coil form concentric with said shaft and having holes at each end thereof on opposite sides of said shaft, said holes being placed at regular intervals around said form, and resilient wires affixed to said shaft and extending substantially radially therefrom with their ends fixedly engaged in said holes to provide torsional resilience between said coil form and said. shaft to minimize breakage of said form.

6. Electric circuit controlling apparatus comprising a rotatable shaft, a cylindrical body mounted on said shaft and supporting an inductance coil, a beryllium-copper conducting shaft parallel to said first shaft and adjacent said coil, a contact wheel on said conducting shaft conductively engaged with said coil to vary the circuit connection therethrough as said coil is rotated, conducting means between said wheel and said conducting shaft to maintain'a wiping metal-to-metal path therebetween, and ball bearings between said wheel and said conducting shaft to maintain alignment therebetween during rotation without lubrication, whereby misalignment between said wheel and said conducting shaft does'not affect said wiping metal-tometal path. I v

7. A mountlngsupport for a frangible body, said'mounting comprising a shaft, said body be'- ing spaced from said shaft and having a recess therein, and a pair of resilient members extending across said shaft, each of said members having a portion fixed to said shaft, the adjacent I free ends of said members tending to remain separated and said ends being flexed into seating engagement and affixed to said body within said recess, said body being supported solely on said shaft through said resilient members which provide torsional resilience therebetween.

8. A mounting support for a frangible body, said support comprising a shaft, said body having portions spaced on opposite sides of said shaft and having a recess in each ofsaid portions, and a pair ofv resilient wires extending across said shaft and having intermediate portions engaged with said shaft on opposite sides thereof, the adjacent free ends of said wires tending to remain separated and said ends being flexed into seating engagement and affixed to said body within said recesses, said body-being supported solely on said shaft through said wires whereby torsional resilience is provided between said body and shaft to minimize breakage of said body.

9. A mounting support for. a frangible body,

said support comprising a shaft, said body having four portions substantially equally spaced around said shaft, each of said portions having a recess therein, a pair of resilient wires extending across said shaft and having intermediate portions engaged with said shaft on opposite sides thereof,

and a second pair of wires similarly engaged with said shaft and extending substantially perpen dicularly to said first pair, the adjacent free ends of said wires tending to remain separated, each pair of said ends being flexed into seating engagement and'amxed to said body within a corresponding recess, said body being supported solely on said shaft through said wires whereby torsional resilience is provided between said shaft and body to minimize said breakage of said body.

10. Electric circuit controlling apparatus comprising a rotatable shaft, a frangible body spaced from said shaft, said .body having recesses therein, and resilient members extending across said shaft, each of said membershaving a portion fixed to said'shaft and a diiferent portion affixed to said frangible body in one of said recesses, said bodybeing supported on said shaft solely through said resilient members whereby torsional resilience is providedbetween said body and said shaft to minimize breakage of said body.

11. Electric circuit controlling apparatus comprising a rotatable shaft, a frangible body having portions spaced on opposite sides of said shaft, each of said portions having a recess therein, and a pair of resilient members having their intermediate portions engaging opposite sides of said shaft and extending across said shaft, the adjacent free ends of said members tending to remain separated, said ends being flexed into seating engagement within'said recesses and being afllxed therein to said frangible body, said members providing the sole support for said body on said shaft whereby torsional resilience is provided between said body and said shaft to mini- 

